Future Stand Development and Potential Fire Behavior following Mountain Pine Beetle
and Harvesting in Colorado Lodgepole Pine Stands
Byron Collins, Michael Battaglia, Rob Hubbard, Chuck Rhoades; U.S. Forest Service, Rocky Mountain Research Station, Fort Collins, CO
Stand Development
Basal Area (m ha
-1
)
30
20
10
10
0
0
0
2
In untreated and harvested beetle-killed stands we:
20
• Measured response of seedling recruitment to overstory mortality
• Used these measurements to predict stand development and
potential fire behavior over time with the Forest Vegetation
Simulator (FVS-FFE)
40
5
4
3
2
1
0
Lodgepole Pine
Untreated
Lodgepole Pine
Subalpine Fir
Engelmann Spruce
Quaking Aspen
Subalpine Fir
Eng. Spruce
Quaking Aspen
Advance
Regeneration
trees ha-1
362 (86)
46 (11)
37 (13)
14 (6)
trees ha-1
562 (104)
956 (193)
75 (19)
1093 (202)
2000
2000
0
0
20
40
60
80
Untreated
Harvested
50
-1
40
30
20
10
0
te
Lit
r
ff
Du
ou
H
1
r
1
ou
H
0
r
ur
dy
en
nd
t
o
o
u
t
o
o
o
S
R
0H
W
0
l
1
00
00
ta
0
10
1
To
Fuel Type
80
Potential Fire Behavior
100
Untreated
97th
90th
80th
50th
100
0
20
40
60
80
100
Years
Passive Crown Fire
Fuel Development
Surface Fire
CBD
0.00
0
Coarse
Fine
Duff
Litter
Snag
Fall
20
0
0
20
40
60
80
20
40
60
80
100
Years
Harvested
0.20
Active/Conditional
Crown Fire
0.15
Untreated
40
0.10
0.05
• After more than a century, subalpine fir will make up the
majority of stand basal area in untreated stands (44%)
while lodgepole pine will be the most common species in
harvested area (53%).
60
0.20
Active/Conditional
Crown Fire
0.15
• Growth simulations predict stand basal area and quadratic
mean diameter will return to pre-outbreak conditions
(~35.5 m2 ha-1 and 13.5 cm, respectively, shaded area) in
both harvested and untreated stands in 75 to 90 years.
Surface Fuel Load (Mg ha-1)
•
Total
woody
surface fuels were
2.6x
higher
in
harvested
areas,
however the larger
size classes, >2.5 cm
(i.e. 100, 1000 hr
fuels),
were
the
greatest contributors.
60
Years
100
Years
Harvested
Surface Fuel Load (Mg ha-1)
Surface Fuels
Fuel Loading (Mg ha )
40
Percentile Weather
4000
0
trees ha-1
305 (108)
1114 (316)
79 (28)
114 (40)
• Lodgepole pine was the most abundant species of
seedling recruitment in harvested areas, 10x more than
untreated areas, the opposite was true of subalpine fir
which was most plentiful in untreated areas.
Salvage logging following MPB
• Stand structure, seedling recruitment and fuel loads were
measured in each unit.
20
6000
4000
Recruitment
(≤ 3 years old)
Harvested
Lodgepole Pine
102 (22)
669 (120)
3135 (714)
Subalpine Fir
20 (8)
272 (103)
144 (40)
Engelmann Spruce
12 (7)
21 (9)
4 (3)
Quaking Aspen
3 (1)
1269 (252)
841 (356)
_______________________________________________________________
*Numbers in parenthesis represent standard error based on 24 units. Advance
regeneration is > 3 years old, < 10 cm DBH.
• Each study site consisted of 6 untreated and 6 harvested units
(n = 24).
0
Total
Pine
Fir
Spruce
Aspen
________________________________________ _____________________________________
Design
100
________________________________________________________________
Study Area
Lodgepole pine mortality from bark beetle
80
6000
Understory Trees
(<10 cm DBH)
Extent of beetle-caused mortality in
Colorado and southern Wyoming.
60
25
Density (trees ha-1)
• Quantified surface and crown fuel profiles
20
Fire following pine beetle caused mortality
60
40
20
• Coarse woody fuels
(> 7.6 cm diameter) are
predicted to increase
2.5x in the first two
decades as standing
dead pine topples.
• Fine fuels (< 7.6 cm)
in harvested areas are
predicted to diminish to
the level of untreated
stands in the first 2
decades
due
to
decomposition and a
minimal input from the
developing canopy.
Canopy Bulk Density (kg m )
Objectives
Untreated
Harvested
Dead Pine
30
Passive Crown Fire
0.10
0.05
Surface Fire
Canopy Bulk Density (kg m )
Composition of overstory trees (> 10 cm DBH)
30
40
3
• 84% of lodgepole basal area is dead, 72% of total BA.
Harvested
Total
Pine
Fir
Spruce
Aspen
40
Basal Area (m2 ha-1)
• Lodgepole pine makes up 86% of total basal area in
our study area.
Untreated
3
Stand Structure
Fire Type
Recent mountain pine beetle (Dendroctonus ponderosae Hopkins)
outbreaks in western North America have set millions of hectares of
forests on to new development trajectories. In Colorado more than
1.2 million hectares of pine forests were affected by bark beetle
infestations between 1996 and 2009. Since 2000, concerns over
increased fuel loads have prompted an unprecedented amount of
harvesting, focused on the removal of dead lodgepole pine.
This study was conducted in four
separate mountain pine beetle
management
areas
located
between 80 and 140 km
northwest of Denver, Colorado.
Study areas were located on US
Forest Service land on the
Medicine
Bow-Routt
and
Arapaho-Roosevelt
National
Forests and on Colorado State
Forest land. Site elevations
ranged from 2661 – 2980 m
above sea level.
Future Conditions
Current Conditions
Fire Type
Overview
0.00
0
20
40
60
80
100
Years
• In the first 15 years, as the canopy develops,
potential fire behavior is not predicted to
differ between untreated and harvested areas.
• Differences in potential fire behavior
between untreated and harvested stands after
the first two decades will be driven by
differences in species composition, associated
canopy bulk density and weather conditions.
0
0
20
40
60
Years
80
100
Presented : August 2011; Austin, TX; Ecological Society of America
Contact Information: bcollins02@fs.fed.us; crhoades@fs.fed.us